1. Field of the Invention
This invention pertains to the general field of vibratory feeders which accept randomly oriented parts and through a combination of rails or tracks and vibratory motion feed these parts properly oriented to a station from which they may be selected for the next step in the production work flow, which may be testing, assembly or packaging. Specifically, the invention pertains to a multiple rail linear feed system for leadless electronic components, commonly known as chips, having electrical terminations on two ends thereof. For testing, further assembly and/or packaging, these chips must be correctly oriented so that the leads of each chip in the feed system are in a predetermined position and correctly aligned or oriented so that they may be picked up mechanically in bulk for the next step in the production process.
2. Background of the Invention
Vibratory feeders have been known in the prior art for some time. Most vibratory feeders in common commercial use are of a circular type. Approximately twenty companies sell circular vibratory feeders in the United States. Two commonly used models are the Syntron model manufactured by Syntron Division, FMC, of Homer City, PA.; and the EA model No. 012 manufactured by Engineered Automation, Inc., High Bridge, N.J.
In a typical circular vibratory feeder, parts are dumped into a vibratory cylindrical bowl having upward spiral tracks on its interior side wall. Centrifugal force caused by the vibratory motion of the bowl forces the parts toward the tracks on the inner perimeter of the bowl. Continuing vibratory motion causes the parts to align themselves lengthwise on these tracks. The combination of these motions plus the pressure from more parts moving from the base perimeter of the bowl forces the oriented parts to move upward gradually on the spiral track of the bowl. As the parts move toward the top of the bowl, they gradually become oriented or aligned on the spiral track. However, a significant number of parts will not be properly oriented. To eliminate these parts from the continuous feed system, one or more discriminators are used along the upper portion of the track. Since the parts are uniform in size dimensions, the discriminators are adjusted so that only properly dimensioned and oriented parts pass through the discriminators. Having passed through the discriminators, the parts are then discharged from the bowl in a linear sequence onto a continuous rail, hopefully properly oriented. In some prior art devices, the discharge chute can cause misalignment and a further discriminator is used on the feed rail. Parts rejected by any of the discriminators are fed or dropped back into the bowl for reprocessing. The typical prior art circular vibratory feeder uses a single channel (rail or track) with a highly complex discriminator unit in the feeder bowl. These units have continuing problems with the jamming of parts in the discriminator areas.
The final output of the typical prior art vibratory feeder is a single track of parts continuously moving down a rail in proper orientation to the next step in the production process. Present day feed rates for chip components range from 5,000 to 15,000 parts per hour.
Linear vibratory feeders are not prominent in the prior art. The present invention is believed to be the first commercially feasible linear vibratory feeder for miniature electronic parts.
Prior art vibratory feeder systems have many inherent limitations. Prime among these is the low rate of feed, about 15,000 parts per hour maximum. Automated systems for handling chip components prior to and subsequent to their handling in the feeders currently are geared to a parts flow of 60,000 to 100,000 parts per hour, 80,000 being a desired goal. In the case of circular vibratory feeders, the placement of complex discriminators within the circular vibrating bowl is inefficient and leads to numerous flow problems. The adjustment of the discriminators is very sensitive and requires frequent manual intervention. Even well-adjusted discriminators reject a high percentage of properly oriented parts, contributing to the low feed rate. Retaining the discriminators within the bowl limits the discharge of oriented parts to a single track or rail of output, further contributing to the low flow rate.
The present invention overcomes the limitation of the prior art by introducing multiple linear rails into the feeder system and placing simple but very efficient discriminators on these rails. The use of multiple rails increases output by a factor of ten in the currently preferred embodiment. The only way to increase the output of prior art, single channel feeders is to increase the feed rate. This causes higher reject rates and more frequent jamming. The placement of simple discriminators along the multiple rails combined with a lower feed rate per channel yields a very fast feed system that is virtually jamproof. The prime purpose of the present invention is to orient electronic chips (leadless components) in multiple rows of single file at the rate of 100,000 per hour without jamming problems. This is achieved by using a fifty-plus channel linear vibratory feeder with discriminators in each channel and a single chip dispenser which randomly distributes chips into the fifty-plus channels.